Wrist salvage procedures alter moment arms of the primary wrist muscles Journal Article

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Authors: Nichols, J. A.; Bednar, M. S.; Havey, R. M.; Murray, W. M.
Article Title: Wrist salvage procedures alter moment arms of the primary wrist muscles
Abstract: BACKGROUND: Proximal row carpectomy and scaphoid-excision four-corner fusion are salvage procedures that relieve pain by removing arthritic joint surfaces. While numerous studies have examined how these procedures affect joint motion, few have examined how they influence muscle mechanical actions. This study examines whether muscle moment arms change after these procedures. METHODS: Moment arms of primary wrist muscles were measured in 8 cadaveric specimens using the tendon excursion method. In each specimen, moment arms were measured for two degrees of freedom (flexion-extension and radial-ulnar deviation) and three conditions (nonimpaired, scaphoid-excision four-corner fusion, and proximal row carpectomy). For each muscle and degree of freedom, moment arm versus joint angle curves for the three conditions were statistically compared. FINDINGS: Wrist salvage procedures significantly alter moment arms of the primary wrist muscles. Proximal row carpectomy primarily alters flexion-extension moment arms, while scaphoid-excision four-corner fusion primarily alters radial-ulnar deviation moment arms. Both procedures also alter the balance between agonist and antagonist wrist muscles. Following proximal row carpectomy, wrist extensors have smaller moment arms in extended postures. Following scaphoid-excision four-corner fusion, radial deviators have larger moment arms throughout radial-ulnar deviation. INTERPRETATION: Different moment arms indicate that different forces are required to complete the same tasks in nonimpaired and surgically altered wrists. The altered muscle moment arms likely contribute to post-operative impairments. Understanding how salvage procedures alter muscle mechanical actions is a critical first step toward identifying the cause of post-operative impairments and is necessary to develop effective interventions to augment deficient muscles and improve overall function.
Journal Title: Clinical biomechanics (Bristol, Avon)
Volume: 30
Issue: 5
ISSN: 1879-1271; 0268-0033
Publisher: Elsevier Inc  
Journal Place: England
Date Published: 2015
Start Page: 424
End Page: 430
Language: eng
DOI/URL:

10.1016/j.clinbiomech.2015.03.015
Notes: LR: 20150513; CI: Copyright (c) 2015; GR: F31 AG041627/AG/NIA NIH HHS/United States; GR: F31 AG041627/AG/NIA NIH HHS/United States; GR: T32 HD007418/HD/NICHD NIH HHS/United States; GR: T32 HD007418/HD/NICHD NIH HHS/United States; JID: 8611877; NIHMS673381; OID: NLM: NIHMS673381 [Available on 06/01/16]; OID: NLM: PMC4428973 [Available on 06/01/16]; OTO: NOTNLM; PMCR: 2016/06/01 00:00; 2014/08/29 [received]; 2015/03/12 [revised]; 2015/03/12 [accepted]; 2015/03/18 [aheadofprint]; ppublish